You mean a door at bottom-right in wolves den right? If you play B! Logan route (courage him to go to bandit camp), you cannot enter to that door. But if you play T! Logan route, you can enter to this by progressing Full moon event.
The door is just a way to the next dungeon where Alpha and Beta wolves were there. The difference between T! and B! Logan is you can found Beta wolf only in T! Logan.
